Tommy Kelly is one huge signing for the Patriots' defense

With the focus during training camp on Tom Brady and the Patriots' revamped receiving corps, the perpetually poor-performing defense has been an uncharacteristic afterthought.

That's a unit that has been the Achilles heel of the Patriots for the past three seasons, ranking 25th, 31st and 25th in total defense while failing to pressure the passer consistently and produce big plays in the biggest games, contributing greatly to a 3-3 playoff record during that span.

Coach Bill Belichick spent another offseason attempting to upgrade his deficient defense. He used five of his seven draft picks on defenders. He re-signed cornerback Aqib Talib, plucked promising lineman Armond Armstead, who is recovering from surgery for an infection and has yet to play this summer, out of the CFL, and took a flier on pass rusher Marcus Benard, who has missed 28 games the last two years due to injury.

But the biggest move — at least literally — was signing defensive tackle Tommy Kelly to a two-year, $5-million deal in April. Kelly is listed at 6-foot-6 and 310 pounds (ha, ha) and is so massive that Vince Wilfork looks as small as Dustin Pedroia next to him.

Kelly and Wilfork, as has been the case since the first day of training camp, were taking up more than a quarter-ton of space in the middle of the 4-3 defense at the start of the Patriots' preseason game with the Tampa Bay Buccaneers on Friday night at Gillette Stadium.

For a defense with a lot of interesting, young pieces, laying a stout foundation is as good a place as any to start.

"If you've got a great defensive line, you can always put yourself in a good position," Kelly said earlier in the week. "A second-and-long situation or put yourself in a situation where you don't have to blitz all the time. You can just rush four.

"So I think any time you've got a real good D-line, that makes more of a great defense. Just look at all the defenses that have been great in the history of this game. They all had A-1 D-lines."

The Patriots know what they have in Wilfork, a first- or second-team All-Pro three years running.

They like what they've seen thus far from Kelly, who is an obvious run-stuffer and historically has been a surprisingly effective pass-rusher.

Although Kelly only had one sack last season, he had 14½ over the previous two years and has recorded at least four sacks in five of his first nine NFL seasons, all of which were spent in Oakland.

"I pretty much know what my job is and I kind of look at it like this — it's a golden opportunity for me," Kelly, 33, said.

"I'm very confident in my ability. I'm very confident in how I fit into this scheme. So I'm just going to keep doing my job every day."

That said, based on what we've seen in training camp and Friday night against the Bucs, it appears Kelly will be subbed out in obvious passing situations. Benard, a hybrid end/linebacker, has been his replacement as of late in the nickel defense.

Kelly was in for six snaps Friday before getting pulled.

That was three more than linebacker Jerod Mayo and two less than Wilfork, the Patriots being content to save the veteran trio for the regular season while also resting defensive backs Devin McCourty, Alfonzo Dennard and Ras-I Dowling for health reasons.

Kelly, who has made 80 straight starts dating back to 2008, is hoping he's in for a long and successful run this fall. He's certainly got it coming.

The Raiders not only didn't make the playoffs during his time there, they never finished with a winning record.

New England hasn't had a losing season since 2000, Belichick's first year here, and have been a postseason participant 10 of the past 12 seasons while reaching five Super Bowls.

"It's a golden opportunity any time you're playing on a team like this," Kelly said. "They've got an opportunity to do something. It's an opportunity, a golden opportunity. It's a better chance than you've probably had in the past, but you've got to take advantage of it."